1. Field of the Invention
The present invention relates to a blower motor for a vehicle air conditioning system.
2. Description of Related Art
In general, a motor main body of a blower motor for a vehicle air conditioning system is received in a motor holder, which is formed through a resin molding process. Radial ribs are formed along an inner surface of the motor holder to project radially inward. The radial ribs are engaged with an outer peripheral surface of a motor yoke of the motor main body to support the motor yoke, so that the motor main body is effectively supported by the motor holder (see, for example, Japanese Unexamined Patent Publication Number 2003-088039, Japanese Unexamined Patent Publication Number 2005-073322 and Japanese Unexamined Patent Publication Number 2000-341898).
Specifically, Japanese Unexamined Patent Publication Number. 2003-088039 discloses the holding structure of the motor, in which the motor main body is received in the motor holder.
Resilient projections are formed in the cylindrical inner peripheral surface of the motor holder at predetermined locations, respectively. The motor main body is supported while the resilient projections are engaged with the outer peripheral surface of the motor yoke.
Since the motor main body is supported by the resilient projections, which are formed in the inner peripheral surface of the motor holder, magnetic sound, which is caused by magnetic vibration of the yoke can be advantageously reduced, and there is no need to use a fixing member for stably holding the motor.
Japanese Unexamined Patent Publication Number 2005-073322 discloses the holding structure of the motor, in which the motor main body is received in the motor holder.
The projections are formed in the inner surface of the motor receiving portion of the motor holder to engage with the outer surface of the motor yoke to support the motor main body.
These projections are provided at an opening of the motor holder and at a location that is away from the opening of the motor holder on one axial side of a motor attachment flange, which is opposite from the opening of the motor holder.
In this way, a vibration transmission path between the opening of the motor holder and the flange is lengthened, so that the vibration is largely attenuated before reaching to the flange.
As described above, the projections, which are formed at predetermined locations in the motor holder, support the motor main body, and the vibration transmission path is lengthened. Therefore, the vibration can be advantageously reduced.
Japanese Unexamined Patent Publication Number 2000-341898 discloses the holding structure of the motor, in which the motor main body is received in the motor holder.
The projections are formed in the interior of the motor case. The projections are formed to support the motor yoke at four locations, i.e., a location of 45 degrees, a location of 135 degrees, a location of 225 degrees and a location of 315 degrees about the motor center relative to a circumferential center of a space between magnets. These locations are at anti-nodes of the vibration, and the vibration can be effectively reduced by fixing the positions of the anti-nodes. Thereby, the generation of the magnetic sound can be effectively limited.
As described above, in Japanese Unexamined Patent Publication Number 2003-088039, Japanese Unexamined Patent Publication Number 2005-073322 and Japanese Unexamined Patent Publication Number 2000-341898, the projections are provided in the supporting member, which receives the motor, and the projections are engaged with the outer peripheral surface of the motor yoke to hold the motor main body. Therefore, the vibration and magnetic sound, which are generated at the time of driving the motor, can be reduced.
Furthermore, the blower motor of the vehicle air conditioning system can be a motor of a left rotating type or a motor of a right rotating type.
In generally, the blower motor of the air conditioning system is located near a driver's seat in a passenger compartment. Thus, in many cases, there are required two types of units, i.e., a unit for a right-hand drive vehicle and a unit for a left-hand drive vehicle, which require opposite air blow directions, respectively.
Therefore, a rotational direction of a fan (i.e., a rotational direction of the motor of the air conditioning system) needs to be changed between these two types. Thus, one of the motor of a left rotating type and the motor of the right rotating type is selected depending on the type of the vehicle.
However, in the cases of Japanese Unexamined Patent Publication Number 2003-088039, Japanese Unexamined Patent Publication Number 2005-073322 and Japanese Unexamined Patent Publication Number 2000-341898, a common motor holder (motor case) is used for the motor of the right rotating type and the motor of the left rotating type to meet a demand of parts commonization. The positions of the projections, which are engaged with the motor yoke to support the motor main body, are kept the same for the motor of the right rotating type and for the motor of the left rotating type. Thus, the motor main body of the motor of the right rotating type and the motor main body of the motor of the left rotating type are held at the same position.
Therefore, the projections, which support the motor main body, are not provided to the best locations, which are best for both of the motor of the right rotating type and the motor of the left rotating type. Thus, when one of the motor main body of the right rotating type and the motor main body of the left rotating type is used, the vibration and noise may become relatively large in comparison to the other one.